There are various forms of pipe machining apparatus known in the art. Some such apparatus are portable and include a frame which can be accurately secured to a pipe. The frame rotatably mounts a tool carrier. A tool head is mounted on the tool carrier whereby a tool may be advanced during rotation of the tool carrier and head to perform a desired cutting operation on the pipe. The tool head usually is incrementally advanced by a tool slide.
Examples of various pipe machining apparatus or portable lathes are shown in U.S. Pat. Nos. 4,791,842; 4,762,038; 4,677,884; 4,655,108; 4,543,861; 4,490,909 and 4,318,391, all of which are assigned to the assignee of this invention.
Most such apparatus have some form of bearing means between the frame which is attached to the pipe and the tool carrier which is rotatably mounted on the frame. Usually, the bearings are rotatably mounted on one of the carrier or frame and travel in a race formed in the other of the carrier or frame. Because of the relative loads imposed between the frame and the rotatable tool carrier during cutting operations, various bearing problems occur. For instance, problems arise due to bearing failure which may result in having to dismantle or replace entire machine parts. A solution to such bearing failure problems is shown in U.S. Pat. No. 4,739,685 wherein a replaceable bearing race is provided.
Another problem involves wear of the bearings during use. Usually, a plurality of roller bearings, or the like, are disposed in the race between the frame and the rotatable tool carrier. As the bearings wear, a smooth rotating operation no longer occurs. In addition, the individual bearings normally will not wear evenly, resulting in a loss of concentricity for the cutting tool whereby precision machining no longer is possible. There is a definite need for an improved pipe machining apparatus which can compensate for wear in the bearing means between the frame and the rotatable tool carrier.
This invention is directed to satisfying such a need and solving the problems referred to above.